This project aims at elucidating the biological function(s) of the normal human c-fps/fes proto-oncogene, and to understand the molecular and cellular basis of its oncogenic potential. We have demonstrated that a cloned human genomic DNA fragment containing c-fps/fes-homologous sequences contains the entire coding sequence of the human c-fps/fes-encoded protein. Our results confirmed that this protein is the 92 Kda cellular tyrosine kinase that we have previously identified as the gene product of human c-fps/fes. Using a retroviral shuttle vector system, we have been able to recover an intron-less copy of human c-fps/fes DNA. We have also identified and begun characterization of a new cellular tyrosine kinase present in all living cells that is immunologically related to the c-fps/fes product, but is encoded by a different gene.